The validity of radiographic assessment of childhood transient synovitis of the hip.

The diagnostic significance of some radiographic signs (abnormal hip 'joint space' and periarticular fat layers) as indicators of hip joint effusion or hip complaints without effusion was studied with ultrasonography and radiography in 47 children (58 examinations), of whom 40 had acute unilateral transient synovitis. It was found that 'joint depth' was not influenced by presence of intra-articular fluid collections; blurring and/or displacement of the periarticular fat pads medial and lateral to the hip joint occurred more frequently when joint effusion was present than in symptom-free hips or in painful hips without effusion. The radiographic signs provided, however, too low diagnostic accuracy to be of practical value. It is suggested that ultrasonography of the hip joint is a valuable means in obtaining a better definition of the diagnosis transient synovitis.